Long-term outcome of patients with perioperative myocardial infarction as diagnosed by troponin I after routine surgical coronary artery revascularization.

Riedel BJ, Grattan A, Martin CB, Gal J, Shaw AD, Royston D
J Cardiothorac Vasc Anesth. 2006 20 (6): 781-7

PMID: 17138080 · DOI:10.1053/j.jvca.2006.01.015

OBJECTIVE - Diagnosis of perioperative myocardial infarction (P-MI) after coronary artery bypass graft (CABG) surgery traditionally relied on a combination of electrocardiographic and enzyme assay changes. Patients with Q-wave P-MIs who survive to hospital discharge have a poorer long-term prognosis. Troponin assays are more sensitive and specific for detecting minor P-MI, with an increased incidence of P-MI being reported. This study investigated if P-MI after CABG surgery, as defined by troponin-I isozyme (cTn-I), correlated with long-term outcome.

DESIGN - A prospective, observational study.

SETTING - A single-institution, cardiothoracic specialty hospital.

PARTICIPANTS - Seventy patients undergoing elective CABG surgery.

INTERVENTIONS - Patients (n = 70) were stratified into low-risk and high-risk groups according to the absence (cTn-I <15 microg/L) or presence (cTn-I >or=15 microg/L) of P-MI after CABG surgery. Patients with (n = 24) and without (n = 46) P-MI were then followed for 3 years after CABG surgery to determine the impact of cTn-I-defined P-MI on long-term outcome.

MEASUREMENTS AND MAIN RESULTS - Most patients felt that their quality of life and activity index had improved and that their symptoms of angina had lessened at 12-month follow-up. However, cardiovascular event-free survival was significantly less in patients with P-MI (p = 0.01) 3 years postoperatively. The incidence for cardiovascular events was 0.24 versus 0.65 (p = 0.049) in those patients without and with P-MI, respectively. The hazard ratio (2.9; 95% confidence interval, 1.3-9.4) for cardiovascular incidents was also significantly greater in patients with P-MI. More specifically, the incidence of arrhythmia was 2.4% versus 26.1% (p < 0.01), and the incidence of vascular events was 4.9% versus 26.1% (p = 0.02) in patients without and with P-MI, respectively.

CONCLUSIONS - It was shown that P-MI as defined by cTn-I is associated with an increased long-term incidence of adverse cardiovascular events. An elevated peak cTn-I level (>or=15 microg/L) identified patients at increased risk but did not have a powerful positive predictive value for either cardiovascular (48%) or vascular (26%) complications. However, a peak cTn-I <15 microg/L was a negative predictor of adverse vascular outcome (95%). This may have implications for postoperative patient follow-up.

MeSH Terms (19)

Cohort Studies Coronary Artery Bypass Coronary Stenosis Disease-Free Survival Follow-Up Studies Humans Incidence Motor Activity Myocardial Infarction Postoperative Complications Predictive Value of Tests Prognosis Prospective Studies Quality of Life Risk Assessment Sensitivity and Specificity Time Treatment Outcome Troponin I

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